The invention relates generally to a method for pretreating continuous textile material having a tufted carpet web and, more particularly, to an improved method for pretreating carpet goods before a dyeing process.
A method and apparatus for pretreating a continuous textile web is disclosed in DE-AS 16 35 004. This document describes guiding a carpet web through a basin of a padding machine or foulard filled with a wetting agent. The wetting agent is squeezed out in a specified manner, and then a dyeing liquid is immediately applied to the web.
Various problems have occurred when tufted carpet webs are pretreated, and subsequently dyed according to the above-described prior art. To lengthen the useful lifetime of the tufting needles used in the ever faster-running tufting machines, larger and larger quantities of finishes or spinning oils must be applied to the fibers. Among their other uses, these finishes and spinning oils are used as lubricants in the carpet tufting process. The finishes and spinning oils remain on the carpet goods and, in conventional dyeing processes, very often result in an uneven fixation of the dye, thus producing cloudy patches and a sandwich effect on the dyed carpet goods. The sandwich effect occurs when the fiber tips are dyed to a lesser degree than the remaining material. The foam used to dye the carpet goods dyes the fiber tips particularly well, and thus, the sandwich effect and the cloudy patches are avoided. However, the finishes and the spinning oils on the carpet web destroy the dyeing foam in the steaming machine and thus the result is a cloudy coloration on the carpet goods.
Problems are caused not only by the quantity of finishes or spinning oils used, but also by the type of finishes or spinning oils that are used. Of course, the price per kilogram of these processing aids is very important. Therefore, inexpensive finishes are often applied to the fibers. Although these inexpensive finishes are effective during the tufting operation, they cause considerable problems during the subsequent dyeing process.
Further problems can occur during the storage of the tufted, untreated carpet material (rolls having a width of 4 to 5 m, for example) over a long period of time. Amongst other things, the carpet edges become damp and then dry out again, which causes the finishes and spinning oils present at the edges to become altered in comparison to the finishes and spinning oils at the middle of the carpet. This nonuniformity may vary the color of the carpet material and result in uneven carpet dyeing over the width of the carpet surface.
When a pretreatment process is carried out in the padding machine, such as disclosed in DE-AS 16 35 004, the finishes and the spinning oils accumulate in the trough of the padding machine and are then subsequently picked up again by the carpet web in a nonuniform manner, thereby interfering with the coloration. When the known technique is used, obstinate coating agents, such as the above-mentioned finishes and spinning oils, cannot be effectively removed.